BRAF mutant non-small cell lung cancer and treatment with BRAF inhibitors
Inhibitors targeting active protein kinases, such as EGFR or ALK, have demonstrated significant efficacy in the treatment of lung cancer. Activating mutations in the MAPK pathway, which includes the enzymes RAS, RAF, MEK, and ERK, result in constitutive signalling, leading to oncogenic cell proliferation and escape from apoptosis; therefore this pathway is a focus of crucial interest for the development of cancer drugs. In melanoma, the most commonly mutated gene is BRAF, with mutations usually occurring in about 50% of all tumours. The BRAF Val600Glu (V600E) mutation constitutes more than 90% of mutations in melanoma. V600E BRAF mutation shows a great dependency on MEK activity, and offers a rational therapeutic strategy for this genetically defined tumour subtype. The use of vemurafenib and dabrafenib, agents that block MAPK signaling in patients with melanoma and the BRAF V600E mutation, has been associated with prolonged survival and progression-free survival. The frequency of V600E BRAF mutation in lung adenocarcinoma is 1.5% to 2.8%. Treatment of V600E BRAF-mutant lung adenocarcinomas with dabrafenib is under evaluation in a phase 2 trial, and could represent another milestone in individualized therapy for lung cancer patients. The next step will be a combination therapy of BRAF inhibitor dabrafenib and MEK inhibitor trametinib.